Aircraft hybrid propulsion train including auxiliary mechanical drive system

Abstract

The present invention discloses a hybrid propulsion chain (1) for an aircraft, the hybrid propulsion chain (1) comprising a plurality of propulsion rotors (R1-RX) electrically connected to a power distribution module (10) via electrical connectors (E1-E4), the power distribution module (10) being connected to a non-propulsion turbine (T) via a power generation system (20) on the one hand, and being electrically connected to a battery (BAT) on the other hand, each propulsion rotor (R1-R4) comprising a stator and at least one rotating shaft, the rotating shaft being configured to rotate relative to the stator when the stator is powered, the hybrid propulsion chain (1) comprising an auxiliary mechanical drive system (30) mechanically connected to the non-propulsion turbine (T), the auxiliary mechanical drive system (30) comprising a plurality of mechanical connectors (M1-M4) for mechanically driving at least one rotating shaft (32) of the propulsion rotor (R1-RX) to rotate.

Description

Technical Field

[0001] The invention relates to the field of aircraft propulsion comprising a number of propulsion rotors powered by non-propulsion electricity generating turbines. Background Art

[0002] As is known, it has been proposed to equip aircraft with a hybrid propulsion system comprising a non-propulsive power generation turbine, batteries and a plurality of electrically driven rotors. This hybrid propulsion system can reduce noise pollution and fuel consumption while achieving optimal transportation of goods and cargo.

[0003] refer to Figure 1 , which shows a hybrid propulsion train 100 of an aircraft of the prior art. In this example, the hybrid propulsion train 100 comprises a plurality of propulsion rotors R1-R4 powered by a power distribution module 110, which is powered on the one hand by a non-propulsion turbine T through a power generation system 120 and on the other hand by a battery BAT. Each propulsion rotor R1-R4 is connected to the power distribution module 110 via one or more power supply buses E1-E4.

[0004] In practice, the battery BAT must be over-configured relative to the normal operating requirements in order to be able to provide additional power in case of temporary needs (such as take-off and landing phases) or special needs (such as evasive maneuvers or circling phases) or when a component of the propulsion chain fails or is unavailable. In terms of the power-to-weight density of current electrochemical batteries, over-configuration of the battery BAT will lead to an increase in the battery volume, thereby limiting the aircraft's load capacity for carrying passengers or cargo.

[0005] One of the objects of the present invention is to provide a hybrid propulsion chain for providing additional mechanical energy in case of unexpected need or in case of failure or unavailability of propulsion chain components, while reducing the size without reducing the ability to carry passengers or cargo.

[0006] Incidentally, an aircraft is known which comprises a mechanically driven propulsion rotor on the one hand and an electrically driven propulsion rotor on the other hand.

[0007] Patent US 2019 / 061924 A1 discloses a propulsion chain consisting of a plurality of propulsion rotors driven by a turbine, and the plurality of propulsion rotors are mechanically driven through a planetary gearbox. Patent US 2018 / 037333 A1 discloses a hybrid propulsion chain including a generator for powering an electric motor. Summary of the invention

[0008] The present invention relates to a hybrid propulsion chain for an aircraft, the hybrid propulsion chain comprising a plurality of propulsion rotors electrically connected to a power distribution module via electrical connectors, the power distribution module being connected to a non-propulsion turbine via a power generation system on the one hand, and to a battery on the other hand, each propulsion rotor comprising a stator and at least one rotating shaft, the rotating shaft being configured to rotate relative to the stator when the stator is powered by at least one electrical connector.

[0009] The present invention is notable in that the hybrid propulsion train comprises an auxiliary mechanical drive system mechanically connected to the non-propulsion turbine, the auxiliary mechanical drive system comprising a plurality of mechanical connections for mechanically driving at least one shaft of the propulsion rotor in rotation.

[0010] A non-propulsive turbine is one that does not directly provide propulsion through a propeller during normal operation. This is in contrast to a turbine equipped with a turbofan. An auxiliary system is a system that is active only when needed. By definition, the term auxiliary device corresponds to "something other than something that is temporary or subordinate".

[0011] By means of the invention, if a hybrid propulsion chain fails without the non-propulsion turbine being unavailable, mechanical power can advantageously be drawn from the non-propulsion turbine to drive one or more propulsion rotors via a mechanical connection. This does not add significant weight, as would be the case with duplicate or redundant batteries, and the reliability of the propulsion chain is improved. Advantageously, the mechanical connection and the electrical connection can be used concomitantly to provide additional propulsion power to the propulsion rotors, for example during take-off or landing, to perform evasive maneuvers, etc.

[0012] Preferably, the power generation system comprises a mechanical distribution module, the input end of which is mechanically connected to the non-propulsion turbine and the output end of which is mechanically connected to at least one current generator. The auxiliary mechanical drive system is connected to the mechanical distribution module. Thus, the auxiliary mechanical drive system is integrated with the power generation system, thereby reducing the overall size and weight.

[0013] Further preferably, the mechanical connector of the auxiliary mechanical drive system is connected to the mechanical distribution module and forms an output of the auxiliary mechanical drive system. Advantageously, the mechanical distribution module is provided with an output for connecting to the current generator and an output for connecting to the mechanical connector, and the structure is compact.

[0014] Preferably, the hybrid propulsion train comprises a mechanical distribution module, the input of which is mechanically connected to the non-propulsion turbine and the output of which is mechanically connected to the power generation system on the one hand and to the auxiliary mechanical drive system on the other hand. The auxiliary mechanical drive system is thus indirectly mechanically connected to the non-propulsion turbine. Advantageously, the mechanical distribution module makes it possible to control the use of mechanical and electric propulsion.

[0015] According to one aspect, each mechanical connection is connected to the rotation shaft of each propulsion rotor in a one-to-one correspondence via a controllable coupling device. This advantageously enables the mechanical drive to be controlled only when needed, preferably providing redundancy.

[0016] Preferably, the controllable coupling device is configured to be automatically activated when the propulsion rotor is powered by the electrical connection and the speed of the shaft of the propulsion rotor decreases relative to its set speed. The coupling device thus improves safety in the event of a malfunction. A speed decrease is a reduction of about 5%-10% of the rated speed within a period of about 1 second.

[0017] According to one aspect, the controllable coupling device comprises at least one flywheel. Advantageously, such a flywheel enables automatic coupling to be performed in case of speed reduction.

[0018] According to another aspect, the controllable coupling device includes at least one first friction member and at least one second friction member.

[0019] According to one aspect, each propulsion rotor comprises at least one propulsion turbofan, preferably two counter-rotating propulsion turbofans.

[0020] The invention also relates to an aircraft comprising a hybrid propulsion chain as described above.

[0021] The invention also relates to a method of using an aircraft as described above, the method comprising:

[0022] driving a plurality of propulsion rotors via electrical connections;

[0023] In case of partial or complete unavailability of the power generation system, at least one of the propulsion rotors is driven via at least one mechanical connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. In the drawings, the same reference numerals are used to indicate similar objects, wherein:

[0025] Figure 1 is a schematic diagram of a hybrid propulsion train of an aircraft in the prior art;

[0026] Figure 2 is a schematic diagram of a hybrid propulsion chain of an aircraft according to a first embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of a hybrid propulsion chain of an aircraft according to a second embodiment of the present invention;

[0028] Figure 4 yes Figure 3 Schematic diagram of the power generation system of the hybrid propulsion chain;

[0029] Figure 5 is a cross-sectional view of a propulsion rotor equipped with a first controllable coupling system according to the present invention;

[0030] Figure 6 is a cross-sectional view of a propulsion rotor equipped with a second controllable coupling system of the present invention;

[0031] Figure 7 is a cross-sectional view of a propulsion rotor of the present invention including two counter-rotating propulsion turbofans; and

[0032] Figure 8 Schematic diagram of a hybrid propulsion chain of an aircraft according to a third embodiment of the present invention.

[0033] It should be noted that these drawings illustrate the invention in a detailed manner to implement the invention, and of course said drawings can be used to better define the invention if necessary. DETAILED DESCRIPTION

[0034] refer to Figure 2 , which shows an embodiment of a hybrid propulsion chain 1 for an aircraft. In this embodiment, the hybrid propulsion chain 1 comprises a plurality of propulsion rotors R1-R4 electrically connected to a power distribution module 10 via electrical connectors E1-E4, the power distribution module 10 being connected to a non-propulsion turbine T via a power generation system 20 on the one hand, and to a battery BAT on the other hand. The battery BAT refers to both a single battery BAT and a group of several batteries BAT.

[0035] The non-propulsion turbomachine T may take various forms, in particular a stationary turbine gas turbine, a free-flowing turbine gas turbine, a piston engine, etc. Advantageously, the non-propulsion turbomachine T is thermal.

[0036] In this embodiment, four propulsion rotors R1-R4 are shown, but it goes without saying that the number of propulsion rotors may be different. Figure 2 As shown, a propulsion rotor RX can be added. Figure 5 and Figure 6 As shown, and will be explained in detail later, each propulsion rotor R1-R4 has a stator 30 and a shaft 32, which is configured to rotate relative to the stator 30 about the axis XS when the stator 30 is energized. Each propulsion rotor R1-R4 includes a propulsion turbofan (not shown) connected to the shaft 32. In this embodiment, each propulsion rotor R1-R4 includes a rotor 31 integrally mounted with the shaft 32. The rotor 31 is magnetically coupled to the stator 30 to form an electric motor of, for example, a permanent magnet synchronous, a wound rotor synchronous, an asynchronous or a reluctance type.

[0037] refer to Figure 7According to one aspect of the invention, each propulsion rotor RC has two counter-rotating propulsion turbofans. For example, the shaft 32 drives a second shaft on which a second turbofan is mounted. In addition, each turbofan may be coated or uncoated and may be steerable or non-steerable. Optionally, each propulsion rotor R1-R4 may include an electrical converter, such as an inverter.

[0038] The power distribution module 10 is well known to those skilled in the art and is capable of managing the power resources of the battery BAT and the power generation system 20 according to the needs of the propulsion rotors R1-R4, the charge level of the battery BAT, the working conditions of the aircraft, etc. The power distribution module 10 is electrically connected to each propulsion rotor R1-R4 through one or more electrical connections E1-E4. Preferably, the power distribution module 10 comprises a power electronic converter for adjusting the level and form (AC / DC) of the voltage as the output of the power generation system 20 when necessary, a driven or non-driven element (junction box, relays ...) ensuring the transmission current, and a driven or non-driven element (circuit breaker, fuse ...) ensuring the safety of goods and personnel.

[0039] In this embodiment, each electrical connector E1-E4 is in the form of a power supply bus, but it goes without saying that different forms may be adopted. Preferably, each electrical connector E1-E4 includes an electrical protection device, specifically a fuse, a circuit breaker, a contactor, etc.

[0040] refer to Figure 5-6 The electrical connectors E1-E4 respectively supply power to the stators 30 of the propulsion rotors R1-R4 so as to magnetically drive the rotors 31 to rotate. Since the rotors 31 are integrally formed with the shaft 32 and the turbofan, the turbofan also rotates accordingly, thereby providing thrust to the propulsion rotors R1-R4.

[0041] As is known, the power generation system 20 comprises one or more current generators and one or more converters, in particular AC-DC type converters. For example, the current generator may take the form of a permanent magnet synchronous motor, a synchronous motor with a wound rotor or an asynchronous motor. Similarly, the converter may take the form of a passive diode rectifier, a passive active rectifier, etc. or a reversible inverter.

[0042] According to the present invention, reference Figure 2 The hybrid propulsion chain 1 comprises an auxiliary mechanical drive system 30 mechanically connected to the non-propulsion turbine T. The auxiliary mechanical drive system 30 comprises a plurality of mechanical connections M1-M4, each of which is used to mechanically drive the rotation shaft 32 of the corresponding propulsion rotor R1-R4 to rotate. Preferably, each of the mechanical connections M1-M4 is in the form of a drive shaft, which is suitable for being driven by the non-propulsion turbine T to rotate.

[0043] In other words, in this embodiment, each propulsion rotor R1-R4 is connected to a corresponding electrical connection E1-E4 on the one hand to receive electrical thrust, and to a corresponding mechanical connection M1-M4 on the other hand to receive mechanical thrust. Therefore, each propulsion rotor R1-R4 is redundant in order to improve the reliability of the hybrid propulsion chain 1.

[0044] According to the first embodiment of the present invention, referring to Figure 2 , the auxiliary mechanical drive system 30 is different from the power generation system 20.

[0045] Preferably, if Figure 2 As shown, the power generation system 20 is connected to an auxiliary mechanical drive system 30, which is configured to output a first mechanical torque for the power generation system 20 and a second mechanical torque for driving the mechanical connections M1-M4. Such an auxiliary mechanical drive system 30 is also referred to as an "auxiliary transmission device".

[0046] According to the second embodiment of the present invention, referring to Figure 3 The auxiliary mechanical drive system 30 is integrally formed with the power generation system 20. This integrated design reduces the overall size and weight. In other words, the power output device is integrated into the power generation system 20.

[0047] For example, refer to Figure 4 The power generation system 20 includes a plurality of current generators G1, G2, GN and a plurality of converters CONV1, CONV2, CONVN to supply power to the power distribution module 10. The power generation system 20 also includes a mechanical distribution module 40, which includes an input terminal E configured to receive input mechanical torque from the non-propulsion turbine T and a plurality of first output terminals S1 that provide basic mechanical torque to the current generators G1, G2, GN to generate electrical energy.

[0048] In this embodiment, the mechanical distribution module 40 also includes a plurality of second output terminals S2 for providing basic mechanical torque to the mechanical connectors M1-M4 to drive the mechanical connectors M1-M4 to rotate. In other words, the mechanical distribution module 40 enables, on the one hand, to provide mechanical energy to indirectly energize the electrical connectors E1-E4, and on the other hand, to provide mechanical energy to directly energize the mechanical connectors M1-M4. Thus, the auxiliary mechanical drive system 30 is directly connected to the mechanical distribution module 40.

[0049] In this embodiment, the mechanical dispensing module 40 includes a plurality of gears, and is preferably in the form of a gear train.

[0050] According to one aspect, the mechanical distribution module 40 is controllable to activate / deactivate the second output S2 according to the operating conditions. As will be explained later, the second output S2 is preferably activated in the event of a power generation failure or when there is an additional propulsion power demand. The additional power demand refers to a power demand greater than 100% of the rated electrical power, preferably less than 130% of the rated electrical power.

[0051] To achieve controllability, the mechanical distribution module 40 includes a controllable decoupling system, such as a clutch, a hydraulic coupling, a dog clutch type, etc.

[0052] According to another embodiment, reference Figure 8 The hybrid propulsion chain 1 comprises a mechanical distribution module 40', the input end of which is mechanically connected to the non-propulsion turbine T, and the output end of which is mechanically connected to the power generation system 20 on the one hand and to the auxiliary mechanical drive system 30 on the other hand. Thus, the auxiliary mechanical drive system 30 is indirectly mechanically connected to the non-propulsion turbine T. Preferably, the power generation system 20 and the auxiliary mechanical drive system 30 remain independent. The structure is parallel.

[0053] Preferably, each mechanical connector M1-M4 is connected to the rotating shaft 32 of each propulsion rotor R1-R4 in a one-to-one correspondence through a controllable coupling device, so that the drive of the rotating shaft 32 of the rotor R1-R4 can be started or stopped through the mechanical connector M1-M4.

[0054] For example, refer to Figure 5 and Figure 6 , which shows a propulsion rotor R1, which includes a stator 30 electrically connected to an electrical connector E1, and a shaft 32 configured to rotate relative to the stator 30 when the stator 30 is energized. The shaft 32 is connected to the mechanical connector M1 via a controllable coupling device 4 to mechanically implement or cut off the coupling between the mechanical connector M1 and the shaft 32.

[0055] refer to Figure 5 According to a first embodiment, the controllable coupling device 4 comprises a flywheel 40. Advantageously, this makes it possible to achieve coupling according to the relative speed of the mechanical connection M1 and the rotating shaft 32. For example, when the speed of the rotating shaft 32 driven by the electrical connection E1 is higher than the speed of the mechanical connection M1, the flywheel 40 does not perform coupling. When the electrical connection E1 stops, the rotation speed of the mechanical connection M1 is higher than the rotation speed of the rotating shaft 32, and the flywheel 40 performs mechanical coupling of the mechanical connection M1 and the rotating shaft 32.

[0056] Advantageously, the controllable coupling device 4 is activated when the speed of the shaft 32 decreases relative to its set speed. Preferably, the hybrid propulsion chain 1 is configured to drive each mechanical connection M1-M4 at the set speed of the propulsion rotors R1-R4. Therefore, the effect is best with the mechanical drive. Preferably, the hybrid propulsion chain 1 is configured to electrically drive each propulsion rotor R1-R4 at a speed higher than the speed of the mechanical connection M1-M4, i.e. higher than the set speed of the propulsion rotors R1-R4. Preferably, this speed is a few percentage points higher than the set speed, for example, about 3%.

[0057] Advantageously, due to the small speed differential, in the event of a power failure, the mechanical connections M1 - M4 automatically take over in a smooth, hassle-free manner.

[0058] refer to Figure 6 According to the second embodiment, the controllable coupling device 4 includes a first friction member 41 integrally formed with the mechanical connection member M1, and a second friction member 42 integrally formed with the rotating shaft 32, the second friction member 42 being configured to cooperate with the first friction member 41 when the mechanical connection member M1 is mechanically coupled to the rotating shaft 32. When the mechanical connection member M1 is not mechanically coupled to the rotating shaft 32, the first friction member 41 is away from the second friction member 42. Such clutch systems are well known in the field of transport vehicles.

[0059] It goes without saying that the mechanical connection M1 can also be directly coupled to the shaft 32, for example, via an angular transmission or a universal joint.

[0060] An embodiment of a hybrid propulsion chain 1 will now be explained.

[0061] During normal operation of the hybrid propulsion train 1, the non-propulsion turbine T generates electrical energy and supplies the propulsion rotors R1-R4 via the electrical connections E1-E4. During this operation, the mechanical connections M1-M4 are not activated.

[0062] In case of a failure of the hybrid propulsion chain 1 without unavailability of the non-propulsion turbine T (specifically a power generation failure), mechanical power can advantageously be drawn from the non-propulsion turbine T to drive one or more propulsion rotors R1-R4 via the activated mechanical connections M1-M4.

[0063] Advantageously, the mechanical connections M1 - M4 and the electrical connections E1 - E4 may be used concomitantly in order to provide additional propulsion power to the propulsion rotors R1 - R4 , for example during take-off or landing, to perform evasive manoeuvres, etc.

[0064] By means of the invention, the hybrid propulsion chain 1 allows weight reduction, thereby improving availability and reliability compared to adding a new battery BAT. Since it is essentially based on mechanical components, the reliability of the auxiliary mechanical drive system 30 is verified. Advantageously, by using the auxiliary mechanical drive system 30, the weight of the battery BAT can be reduced, thereby meeting different propulsion requirements.

Claims

1. A hybrid propulsion chain (1) for an aircraft, the hybrid propulsion chain (1) comprising a plurality of propulsion rotors (R1-RX) electrically connected to a power distribution module (10) via electrical connectors (E1-E4), the power distribution module (10) being connected to a non-propulsion turbine (T) via a power generation system (20) on the one hand, and to a battery (BAT) on the other hand, each propulsion rotor (R1-R4) comprising a stator (30) and at least one rotating shaft (32), the rotating shaft being configured to rotate relative to the stator (30) when the stator (30) is powered by at least one electrical connector (E1-E4), wherein: The hybrid propulsion chain includes an auxiliary mechanical drive system (30) mechanically connected to the non-propulsion turbine (T), and the auxiliary mechanical drive system (30) includes a plurality of mechanical connectors (M1-M4) for mechanically driving the rotation shaft (32) of the propulsion rotor (R1-R4) to rotate, and each mechanical connector (M1-M4) is connected to the rotation shaft (32) of each propulsion rotor (R1-R4) in a one-to-one correspondence through a controllable coupling device (4).

2. The hybrid propulsion chain (1) according to claim 1, characterized in that: The power generation system (20) comprises a mechanical distribution module (40), the input end of the mechanical distribution module (40) is mechanically connected to the non-propulsion turbine (T), the output end of the mechanical distribution module (40) is mechanically connected to at least one current generator (G1, G2, GN), and the auxiliary mechanical drive system (30) is connected to the mechanical distribution module (40).

3. The hybrid propulsion chain (1) according to claim 2, characterized in that: The mechanical connectors (M1-M4) of the auxiliary mechanical drive system (30) are connected to the mechanical distribution module (40) and form the output end of the auxiliary mechanical drive system (30).

4. The hybrid propulsion chain (1) according to claim 1, characterized in that: It comprises a mechanical distribution module (40'), the input end of which is mechanically connected to the non-propulsion turbine (T), and the output end of which is mechanically connected to the power generation system (20) on the one hand and to the auxiliary mechanical drive system (30) on the other hand.

5. The hybrid propulsion chain (1) according to claim 1, characterized in that: The controllable coupling device (4) is configured to be automatically activated when the propulsion rotor (R1-R4) is powered by the electrical connection (E1-E4) and the speed of the rotation shaft (32) of the propulsion rotor (R1-R4) decreases relative to its set speed.

6. The hybrid propulsion chain (1) according to claim 5, characterized in that The controllable coupling device (4) comprises at least one flywheel.

7. The hybrid propulsion chain (1) according to claim 5, characterized in that: The controllable coupling device (4) comprises at least one first friction member (41) and at least one second friction member (42).

8. The hybrid propulsion chain (1) according to any one of claims 1 to 7, characterized in that: Each propulsion rotor (R1-R4) comprises at least one propulsion turbofan.

9. An aircraft, characterized in that: Comprising a hybrid propulsion chain (1) as claimed in any one of claims 1 to 8.

10. A method of using an aircraft as claimed in claim 9, characterized in that: The method comprises: - driving a plurality of propulsion rotors (R1-RX) via said electrical connections (E1-E4); - In the event of partial or complete unavailability of said power generation system (20), driving at least one propulsion rotor (R1-RX) through at least one mechanical connection (M1-M4).

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